mp3 organising problem

hi guys i just wanted to know how to fix this problem

i created a good few playlists on my pc using wmp11 but now i renamed some files using godafather and i also re organised my music files on my hard drive,

now most of my playlists wont play as wmp11 "cant find" the files

is there a possible fix to this problem or is it irrepairable

also as time goes by im going to be moving files so does anybody have any reccomendations on a programme that is very easy to create mp3 playlists ( which wont cease to work if i move a file etc ) and also connect and transfer music to standard mp3 players etc

thanks guys

ferg